TY  - JOUR
A1  - Tötzke, Christian
A1  - Manke, Ingo
A1  - Gaiselmann, Gerd
A1  - Bohner, John
A1  - Müller, Bernd R.
A1  - Kupsch, Andreas
A1  - Hentschel, Manfred P.
A1  - Schmidt, Volker
A1  - Banhart, Jens
A1  - Lehnert, Werner
T1  - A dedicated compression device for high resolution X-ray tomography of compressed gas diffusion layers
JF  - Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques
N2  - We present an experimental approach to study the three-dimensional microstructure of gas diffusion layer (GDL) materials under realistic compression conditions. A dedicated compression device was designed that allows for synchrotron-tomographic investigation of circular samples under well-defined compression conditions. The tomographic data provide the experimental basis for stochastic modeling of nonwoven GDL materials. A plain compression tool is used to study the fiber courses in the material at different compression stages. Transport relevant geometrical parameters, such as porosity, pore size, and tortuosity distributions, are exemplarily evaluated for a GDL sample in the uncompressed state and for a compression of 30 vol.%. To mimic the geometry of the flow-field, we employed a compression punch with an integrated channel-rib-profile. It turned out that the GDL material is homogeneously compressed under the ribs, however, much less compressed underneath the channel. GDL fibers extend far into the channel volume where they might interfere with the convective gas transport and the removal of liquid water from the cell. (C) 2015 AIP Publishing LLC.
Y1  - 2015
U6  - https://doi.org/10.1063/1.4918291
SN  - 0034-6748
SN  - 1089-7623
VL  - 86
IS  - 4
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Fazeli, Mohammadreza
A1  - Hinebaugh, James
A1  - Fishman, Zachary
A1  - Tötzke, Christian
A1  - Lehnert, Werner
A1  - Manke, Ingo
A1  - Bazylak, Aimy
T1  - Pore network modeling to explore the effects of compression on multiphase transport in polymer electrolyte membrane fuel cell gas diffusion layers
JF  - Journal of power sources : the international journal on the science and technology of electrochemical energy systems
N2  - Understanding how compression affects the distribution of liquid water and gaseous oxygen in the polymer electrolyte membrane fuel cell gas diffusion layer (GDL) is vital for informing the design of improved porous materials for effective water management strategies. Pore networks extracted from synchrotron-based micro-computed tomography images of compressed GDLs were employed to simulate liquid water transport in GDL materials over a range of compression pressures. The oxygen transport resistance was predicted for each sample under dry and partially saturated conditions. A favorable GDL compression value for a preferred liquid water distribution and oxygen diffusion was found for Toray TGP-H-090 (10%), yet an optimum compression value was not recognized for SGL Sigracet 25BC. SGL Sigracet 25BC exhibited lower transport resistance values compared to Toray TGP-H-090, and this is attributed to the additional diffusion pathways provided by the microporous layer (MPL), an effect that is particularly significant under partially saturated conditions. (C) 2016 Elsevier B.V. All rights reserved.
KW  - Pore network modeling
KW  - Synchrotron X-ray
KW  - Computed tomography
KW  - Liquid water distribution
KW  - Gas diffusion layer
KW  - Compression
Y1  - 2016
U6  - https://doi.org/10.1016/j.jpowsour.2016.10.039
SN  - 0378-7753
SN  - 1873-2755
VL  - 335
SP  - 162
EP  - 171
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Tötzke, Christian
A1  - Gaiselmann, G.
A1  - Osenberg, M.
A1  - Arlt, T.
A1  - Markötter, H.
A1  - Hilger, A.
A1  - Kupsch, Andreas
A1  - Müller, B. R.
A1  - Schmidt, V.
A1  - Lehnert, W.
A1  - Manke, Ingo
T1  - Influence of hydrophobic treatment on the structure of compressed gas diffusion layers
JF  - Journal of power sources : the international journal on the science and technology of electrochemical energy systems
N2  - Carbon fiber based felt materials are widely used as gas diffusion layer (GDL) in fuel cells. Their transport properties can be adjusted by adding hydrophobic agents such as polytetrafluoroethylene (PTFE). We present a synchrotron X-ray tomographic study on the felt material Freudenberg H2315 with different PIPE finishing. In this study, we analyze changes in microstructure and shape of GDLs at increasing degree of compression which are related to their specific PTFE load. A dedicated compression device mimicking the channel-land pattern of the flowfield is used to reproduce the inhomogeneous compression found in a fuel cell. Transport relevant geometrical parameters such as porosity, pore size distribution and geometric tortuosity are calculated and consequences for media transport discussed. PTFE finishing results in a marked change of shape of compressed GDLs: surface is smoothed and the invasion of GDL fibers into the flow field channel strongly mitigated. Furthermore, the PTFE impacts the microstructure of the compressed GDL. The number of available wide transport paths is significantly increased as compared to the untreated material. These changes improve the transport capacity liquid water through the GDL and promote the discharge of liquid water droplets from the cell. (C) 2016 Elsevier B.V. All rights reserved.
KW  - Gas diffusion layer
KW  - Synchrotron tomography
KW  - Compression
KW  - Hydrophobic treatment
KW  - Water transport
Y1  - 2016
U6  - https://doi.org/10.1016/j.jpowsour.2016.05.118
SN  - 0378-7753
SN  - 1873-2755
VL  - 324
SP  - 625
EP  - 636
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Shashev, Yury
A1  - Kupsch, Andreas
A1  - Lange, Axel
A1  - Evsevleev, Sergei
A1  - Müller, Bernd R.
A1  - Osenberg, Markus
A1  - Manke, Ingo
A1  - Hentschel, Manfred P.
A1  - Bruno, Giovanni
T1  - Optimizing the visibility of X-ray phase grating interferometry
JF  - Materials testing : Materialprüfung ; materials and components, technology and application
N2  - The performance of grating interferometers coming up now for imaging interfaces within materials depends on the efficiency (visibility) of their main component, namely the phase grating. Therefore, experiments with monochromatic synchrotron radiation and corresponding simulations are carried out. The visibility of a phase grating is optimized by different photon energies, varying detector to grating distances and continuous rotation of the phase grating about the grid lines. Such kind of rotation changes the projected grating shapes, and thereby the distribution profiles of phase shifts. This yields higher visibilities than derived from ideal rectangular shapes. By continuous grating rotation and variation of the propagation distance, we achieve 2D visibility maps. Such maps provide the visibility for a certain combination of grating orientation and detector position. Optimum visibilities occur at considerably smaller distances than in the standard setup.
KW  - X-ray imaging
KW  - grating interferometry
KW  - Talbot-Lau interferometer
KW  - X-ray refraction
KW  - X-ray phase contrast
Y1  - 2017
U6  - https://doi.org/10.3139/120.111097
SN  - 0025-5300
VL  - 59
SP  - 974
EP  - 980
PB  - Hanser
CY  - München
ER  - 
TY  - JOUR
A1  - Tötzke, Christian
A1  - Kardjilov, Nikolay
A1  - Manke, Ingo
A1  - Oswald, Sascha
T1  - Capturing 3D Water Flow in Rooted Soil by Ultra-fast Neutron Tomography
JF  - Scientific reports
N2  - Water infiltration in soil is not only affected by the inherent heterogeneities of soil, but even more by the interaction with plant roots and their water uptake. Neutron tomography is a unique non-invasive 3D tool to visualize plant root systems together with the soil water distribution in situ. So far, acquisition times in the range of hours have been the major limitation for imaging 3D water dynamics. Implementing an alternative acquisition procedure we boosted the speed of acquisition capturing an entire tomogram within 10 s. This allows, for the first time, tracking of a water front ascending in a rooted soil column upon infiltration of deuterated water time-resolved in 3D. Image quality and resolution could be sustained to a level allowing for capturing the root system in high detail. Good signal-to-noise ratio and contrast were the key to visualize dynamic changes in water content and to localize the root uptake. We demonstrated the ability of ultra-fast tomography to quantitatively image quick changes of water content in the rhizosphere and outlined the value of such imaging data for 3D water uptake modelling. The presented method paves the way for time-resolved studies of various 3D flow and transport phenomena in porous systems.
Y1  - 2017
U6  - https://doi.org/10.1038/s41598-017-06046-w
SN  - 2045-2322
VL  - 7
PB  - Macmillan Publishers Limited
CY  - London
ER  - 
TY  - GEN
A1  - Tötzke, Christian
A1  - Kardjilov, Nikolay
A1  - Manke, Ingo
A1  - Oswald, Sascha
T1  - Capturing 3D Water Flow in Rooted Soil by Ultra-fast Neutron Tomography
N2  - Water infiltration in soil is not only affected by the inherent heterogeneities of soil, but even more by the interaction with plant roots and their water uptake. Neutron tomography is a unique non-invasive 3D tool to visualize plant root systems together with the soil water distribution in situ. So far, acquisition times in the range of hours have been the major limitation for imaging 3D water dynamics. Implementing an alternative acquisition procedure we boosted the speed of acquisition capturing an entire tomogram within 10 s. This allows, for the first time, tracking of a water front ascending in a rooted soil column upon infiltration of deuterated water time-resolved in 3D. Image quality and resolution could be sustained to a level allowing for capturing the root system in high detail. Good signal-to-noise ratio and contrast were the key to visualize dynamic changes in water content and to localize the root uptake. We demonstrated the ability of ultra-fast tomography to quantitatively image quick changes of water content in the rhizosphere and outlined the value of such imaging data for 3D water uptake modelling. The presented method paves the way for time-resolved studies of various 3D flow and transport phenomena in porous systems
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 385 
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-402237
ER  - 
TY  - JOUR
A1  - Toetzke, Christian
A1  - Kardjilov, Nikolay
A1  - Manke, Ingo
A1  - Oswald, Sascha
T1  - Capturing 3D Water Flow in Rooted Soil by Ultra-fast Neutron Tomography
JF  - Scientific reports
N2  - Water infiltration in soil is not only affected by the inherent heterogeneities of soil, but even more by the interaction with plant roots and their water uptake. Neutron tomography is a unique non-invasive 3D tool to visualize plant root systems together with the soil water distribution in situ. So far, acquisition times in the range of hours have been the major limitation for imaging 3D water dynamics. Implementing an alternative acquisition procedure we boosted the speed of acquisition capturing an entire tomogram within 10 s. This allows, for the first time, tracking of a water front ascending in a rooted soil column upon infiltration of deuterated water time-resolved in 3D. Image quality and resolution could be sustained to a level allowing for capturing the root system in high detail. Good signal-to-noise ratio and contrast were the key to visualize dynamic changes in water content and to localize the root uptake. We demonstrated the ability of ultra-fast tomography to quantitatively image quick changes of water content in the rhizosphere and outlined the value of such imaging data for 3D water uptake modelling. The presented method paves the way for time-resolved studies of various 3D flow and transport phenomena in porous systems.
Y1  - 2017
U6  - https://doi.org/10.1038/s41598-017-06046-w
SN  - 2045-2322
VL  - 7
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Sun, Fu
A1  - Osenberg, Markus
A1  - Dong, Kang
A1  - Zhou, Dong
A1  - Hilger, Andre
A1  - Jafta, Charl J.
A1  - Risse, Sebastian
A1  - Lu, Yan
A1  - Markoetter, Henning
A1  - Manke, Ingo
T1  - Correlating Morphological Evolution of Li Electrodes with Degrading Electrochemical Performance of Li/LiCoO2 and Li/S Battery Systems
BT  - Investigated by Synchrotron X-ray Phase Contrast Tomography
JF  - ACS energy letters / American Chemical Society
N2  - Efficient Li utilization is generally considered to be a prerequisite for developing next-generation energy storage systems (ESSs). However, uncontrolled growth of Li microstructures (LmSs) during electrochemical cycling has prevented its practical commercialization. Herein, we attempt to understand the correlation of morphological evolution of Li electrodes with degrading electrochemical performances of Li/LiCoO2 and Li/S systems by synchrotron X-ray phase contrast tomography technique. It was found that the continuous transformation of the initial dense Li bulk to a porous lithium interface (PL1) structure intimately correlates with the gradually degrading overall cell performance of these two systems. Additionally, the formation mechanism of the PLI and its correlation with previously reported inwardly growing LmS and the lithium-reacted region have been intensively discussed. The information that we gain herein is complementary to previous investigations and may provide general insights into understanding of degradation mechanisms of Li metal anodes and also provide highly needed guidelines for effective design of reliable next-generation Li metal-based ESSs.
Y1  - 2018
U6  - https://doi.org/10.1021/acsenergylett.7b01254
SN  - 2380-8195
VL  - 3
IS  - 2
SP  - 356
EP  - 365
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Sun, Fu
A1  - Dong, Kang
A1  - Osenberg, Markus
A1  - Hilger, Andre
A1  - Risse, Sebastian
A1  - Lu, Yan
A1  - Kamm, Paul H.
A1  - Klaus, Manuela
A1  - Markoetter, Henning
A1  - Garcia-Moreno, Francisco
A1  - Arlt, Tobias
A1  - Manke, Ingo
T1  - Visualizing the morphological and compositional evolution of the interface of InLi-anode|thio-LISION electrolyte in an all-solid-state Li-S cell by in operando synchrotron X-ray tomography and energy dispersive diffraction
JF  - Journal of materials chemistry : A, Materials for energy and sustainability
N2  - Dynamic and direct visualization of interfacial evolution is helpful in gaining fundamental knowledge of all-solid-state-lithium battery working/degradation mechanisms and clarifying future research directions for constructing next-generation batteries. Herein, in situ and in operando synchrotron X-ray tomography and energy dispersive diffraction were simultaneously employed to record the morphological and compositional evolution of the interface of InLi-anode|sulfide-solid-electrolyte during battery cycling. Compelling morphological evidence of interfacial degradation during all-solid-state-lithium battery operation has been directly visualized by tomographic measurement. The accompanying energy dispersive diffraction results agree well with the observed morphological deterioration and the recorded electrochemical performance. It is concluded from the current investigation that a fundamental understanding of the phenomena occurring at the solid-solid electrode|electrolyte interface during all-solid-state-lithium battery cycling is critical for future progress in cell performance improvement and may determine its final commercial viability.
Y1  - 2018
U6  - https://doi.org/10.1039/c8ta08821g
SN  - 2050-7488
SN  - 2050-7496
VL  - 6
IS  - 45
SP  - 22489
EP  - 22496
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Herppich, Werner B.
A1  - Martin, Craig E.
A1  - Tötzke, Christian
A1  - Manke, Ingo
A1  - Kardjilov, Nikolay
T1  - External water transport is more important than vascular transport in the extreme atmospheric epiphyte Tillandsia usneoides (Spanish moss)
JF  - Plant, cell & environment : cell physiology, whole-plant physiology, community physiology
N2  - Most epiphytic bromeliads, especially those in the genus Tillandsia, lack functional roots and rely on the absorption of water and nutrients by large, multicellular trichomes on the epidermal surfaces of leaves and stems. Another important function of these structures is the spread of water over the epidermal surface by capillary action between trichome "wings" and epidermal surface. Although critical for the ultimate absorption by these plants, understanding of this function of trichomes is primarily based on light microscope observations. To better understand this phenomenon, the distribution of water was followed by its attenuation of cold neutrons following application of H2O to the cut end of Tillandsia usneoides shoots. Experiments confirmed the spread of added water on the external surfaces of this "atmospheric" epiphyte. In a morphologically and physiologically similar plant lacking epidermal trichomes, water added to the cut end of a shoot clearly moved via its internal xylem and not on its epidermis. Thus, in T. usneoides, water moves primarily by capillarity among the overlapping trichomes forming a dense indumentum on shoot surfaces, while internal vascular water movement is less likely. T. usneoides, occupying xeric microhabitats, benefits from reduction of water losses by low-shoot xylem hydraulic conductivities.
KW  - bromeliads
KW  - capillarity
KW  - cold neutrons
KW  - epidermis
KW  - epiphytes
KW  - trichomes
KW  - water movement
Y1  - 2018
U6  - https://doi.org/10.1111/pce.13496
SN  - 0140-7791
SN  - 1365-3040
VL  - 42
IS  - 5
SP  - 1645
EP  - 1656
PB  - Wiley
CY  - Hoboken
ER  -